Plasma display panel having display and counter conductors on one plate

ABSTRACT

A plasma display panel of the gas discharge type comprising a plurality of discrete electrically excitable gas-containing cells. Associated with each cell is a conductor array comprising a plurality of segments and a corresponding common conductor all positioned on the same surface. A transparent dielectric film is deposited over each segment conductor array and each corresponding common conductor, so that all the conductors are capacitively coupled, but physically isolated from the excitable gas. A particular character is displayed on the plasma display device by alternately energizing a selected one of the segment conductors comprising the segment conductor array and the corresponding common conductor. The excitable gas immediately adjacent the energized segment conductors and the corresponding common conductor is ionized, with a resulting illumination which is visible to the human eye. The resulting illumination is confined to the area circumscribed by the energized segment conductors and the corresponding common conductor. In order to conceal the illumination generated by the common conductor, a mask is provided which contains a plurality of openings generally conforming in shape to the segmented conductor array and so positioned that the openings are aligned with a corresponding segment conductor. The illumination provided by the occurrence of the ionization is sufficient for the visual display of numeric, symbolic, and alphabetic information. The plasma display panel is hermetically sealed in order to prevent the escape of any of the excitable gas into the atmosphere.

United States Patent Janning [54] PLASMA DISPLAY PANEL HAVING DISPLAYAND COUNTER CONDUCTORS ON ONE PLATE [72] Inventor:

[73] Assignee: The National Cash Register Company,

Dayton, Ohio 22 Filed: July 20,1970

211 Appl.No.: 56,396

John L. Jannlng, Dayton, Ohio [52] US. Cl ..313/109.5, 313/220, 315/169TV 25,496 10/1968 Japan ..313/l09.5

Primary Examiner-Roy Lake Assistant ExaminerPalmer C. DemeoAttarneyLouis A. Kline, Albert L. Sessler, Jr. and Gustalo Nunez [451Mar. 28, 1912 [57] ABSTRACT A plasma display panel of the gas dischargetype comprising a plurality of discrete electrically excitablegas-containing cells. Associated with each cell is a conductor arraycomprising a plurality of segments and a corresponding common conductorall positioned on the same surface. A transparent dielectric film isdeposited over each segment conductor array and each correspondingcommon conductor, so that all the conductors are capacitively coupled,but physically isolated from the excitable gas.

A particular character is displayed on the plasma display device byalternately energizing a selected one of the segment conductorscomprising the segment conductor array and the corresponding commonconductor. The excitable gas immediately adjacent the energized segmentconductors and the corresponding common conductor is ionized, with aresulting illumination which is visible to the human eye. The resultingillumination is confined to the area circumscribed by the energizedsegment conductors and the corresponding common conductor. In order toconceal the illumination generated by the common conductor, a mask isprovided which contains a plurality of openings generally conforming inshape to the segmented conductor array and so positioned that theopenings are aligned with a corresponding segment conductor. Theillumination provided by the occurrence of the ionization is sufficientfor the visual display of numeric, symbolic, and alphabetic information.The plasma display panel is hermetically sealed in order to prevent theescape of any of the excitable gas into the atmosphere.

4 Claims, 2 Drawing Figures Pmimmm m2 INVENTOR JOHN L. JA

MMq/ M W HIS ATTORNEYS PLASMA DISPLAY PANEL HAVING DISPLAY AND COUNTERCONDUCTORS ON ONE PLATE BACKGROUND OF THE INVENTION This inventionrelates to a plasma display panel.

Plasma display devices (or electroluminescent display devices, as theyare sometimes referred to) which produce a glow upon the application ofan electric field across a cell containing an excitable gas are wellknown. Devices of this type are exemplified in U.S. Pat. No. 3,127,535,issued Mar. 31, 1964, to Harold T. Westerheim; U.S. Pat. No. 3,327,154,issued June 20, 1967, on the application of Edwin R. Bowerman; U.S. Pat.No. 3,499,167, issued Mar. 3, 1970, on the application of Theodore C.Baker et al.; and British Pat. Nos. 1,161,832 and 1,161,833, both ofwhich are owned by the University of Illinois Foundation.

A problem generally common to most plasma and electroluminescent devicesis the inability to provide a structure which has small physicaldimensions and which is also capable of simple and inexpensivefabrication. The prior art devices are characteristic in that theyutilize conductors which are physically opposed to each other; that is,on different plane surfaces and separated from each other by theintervening excitable gas. This type of structure requires thedeposition of conductors on a plurality of plates, which increases thecost of fabricationfApplicants structure is novel in that it is a simplestructure in which all the conductors are deposited on only one surfaceof the plasma panel. Applicants structure also provides a display deviceparticularly suited for AC operation with voltages of relatively lowmagnitude.

SUMMARY OF THE INVENTION This invention relates to a hermetically sealedplasma display panel comprising first, second, and third plates, thesecond plate defining a plurality of cells when positioned between thefirst and third plates, wherein said defined cells are utilized for thecontainment of an excitable gas. On one side of each of the formed cellsare positioned a segmented conductor array and a common conductor, theaforementioned conductors all being physically separated from the cellinterior by a layer of a dielectric material such as glass. Each formedcell is capable of displaying information in the form of illuminatedcharacters. The illumination necessary for the viewing of information ona particular cell is provided by applying an alternating electricpotential across the common conductor and a selected segment conductoror selected segment conductors of the segmented array of conductorscorresponding to the cell selected for illumination. The alternatingpotential gives rise tothe ionization of gas immediately adjacent thoseenergized conductors. The illumination provided by the excited gas isrestricted to the areas immediately adjacent the energized conductorsbecause of the pressure and the composition of the gas.

A nonconductive mask, having a plurality of openings therein, eachopening generally having the same configuration and corresponding to oneof the segment conductors, is positioned in the panel in such a mannerthat the openings in the mask are in alignment with the segmentconductors of the segmented conductor array. The insulating maskseliminates any stray illumination which may occur due to changes in thepressure and also eliminates any illumination caused by the conductorswhich connect like segments of each cell to a power source. Theinsulating mask also prevents a viewer from observing the illuminationadjacent the energized common conductor. The entire assembly is sealedby conventional glass sealing methods in order to prevent the escape ofany excitable gas. In a second embodiment of the invention, the commonconductor is illustrated in a position different from that of the firstembodiment.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an exploded isometric view ofthe plasma display panel in accordance with the invention.

FIG. 2 is a partial view of a second embodiment of the invention, inwhich the common conductor is shown vertically disposed adjacent thesegmented conductor array.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the plasmadisplay panel is shown generally at 10. The panel includes plates 12 and18, each having first and second sides, respectively. The plates 12 and18 are preferably fabricated from a glass material. At least one of theplates is transparent or translucent, preferably the plate 12. The firstside of the plate 18 has deposited thereon, by conventional techniquessuch as vacuum deposition, silk screening, electrolytic deposition,etc., a plurality of segmented conductor arrays 20a-n, each arraycomprising a plurality of segment conductors 2la-g. Each of thesegmented conductor arrays 20a-n illustrated in FIG. 1 is shown as aseven-segment array, which may be utilized to form numerals. However, anarray containing any number of segment conductors may be utilized inthis invention without departing from the teachings thereof. Alsoconventionally deposited on the first side of the plate 18 are aplurality of common conductors 2 2un, which function as the common foreach segment conductor of the arrays 20a-n, respectively. For purposesof simplicity in the description of the invention, only one display cellwill be discussed. Therefore, unless otherwise noted, the segmentconductors will be referred to by the reference numeral 21, an array bythe reference numeral 20, and a common conductor by the referencenumeral 22. The surface area of the common conductor 22 is greater thanthe surface area of any of the segment conductors in the segmentedconductor array 20 and should also be greater than the combined surfacearea of at least half of the combined segment conductors 21 in order tolessen the current density experienced by the common conductor 22 when aplurality of the segment conductors 21 are energized in order to displaya number; for example, the number 8. A segmented conductor array 20 anda corresponding common conductor 22 are deposited on the first side ofthe plate 18 for each cell formed in the plasma display panel 10. It isnoted that all corresponding segment conductors 21 of each segmentedconductor array 20 are connected together by conductors 30 and broughtout to a terminal 26 for connection to a power source (not shown).However, if desired, each segment conductor 21 may be brought outindividually and connected to a power source. The mode of connecting thecorresponding segment conductors is determined by the type of operationwhich the plasma panel will undergo. A thin transparent, translucent, oropaque dielectric layer 24, preferably glass, is deposited over all thesegment and common conductors located on the first side of the plate 18.

A spacing member 16, containing a plurality of openings defined by aplurality of frame members 28, is placed intermediate the plates 12 and18. Each opening on the spacing member 16 defines one cell, whichincludes a segmented conductor array 20 and one common conductor 22.Each segmented conductor array 20 and the corresponding common conductor22 are separated from any other adjacent segmented conductor array andits corresponding common conductor by the frame members 28, which areintegral to the spacing member 16. The surface of the spacing member 16is of such a roughness that gas can pass from one cell to another, thusproviding cell pressure equalization. Although the spacing member 16 isshown as a rigid body containing a plurality of openings, the spacingmember 16 may be eliminated, if desired, by placing a wall formation ofglass-like material on the first side of the plate 18 between eachcombination of segmented conductor arrays and the corresponding commonconductor in order to separate each segmented conductor array andcorresponding common conductor from adjacent combinations of arrays andcommon conductors, thereby defining a plurality of cells.

A mask '14, containing a plurality of openings thereon, is provided,each opening corresponding to one segment conductor 21 of each of theconductor arrays 20 positioned on the plate 18 for the purpose offurther defining the illumination which emanates from the energizedsegment conductors 21 and also for concealing the illumination generatedby the common conductor 22. The mask 14 also conceals any illuminationprovided by the connecting segment conductors 30. It is noted that thedisplay panel does not require the mask 14 for its successful operation,since the illumination generated is restricted to the surfaces of theenergized segment conductors and the common conductors 22. The mask 14is shown as being stippled in order to illustrate that the mask 14 isdark in color.

The transparent plate 12 completes the assembly comprising thetransparent plate 12, the mask member 14, the spacing member 16, and therear plate 18. A thixotropic slip is made with glass frit and applied tothe periphery of the assembly 10 in such a manner as to provide agastight seal when properly cured. A glass tube (not shown) may besecured to the rear of the plate 18 in a similar manner, to be utilizedfor evacuating the plasma cells of air and for introducing the excitablegas, such as a mixture of neon, argon, and nitrogen, into those cells.As previously described, the terminals 26 and the common conductors 22are connected to an alternating potential source (not shown) for thepurpose of providing the alternating electric field.

Prior to a discussion of the operation of the plasma display panel 10,it would be in order to discuss some of the fundamental rules whichapply to this type of display cell. Ionization in this type of cell isinitiated by an alternating electric field which causes an electronmultiplication process to occur in the area immediately adjacent theconductors which are experiencing the alternating electrical field. Thismultiplication process occurs until ignition (that is, ionization), atwhich time a gaseous discharge occurs, which provides the illuminationnecessary for the character display. The ionization of the gas alsoresults in the deposition of electrical charges on the energized segmentconductors and corresponding common conductor. The charges will have apolarity opposed to that which was impressed on the common and segmentconductors and may be utilized in the control of the plasma displaypanel. The above process is reversible due to the alternating electricfield, which is made necessary because the conductors are separated fromthe excitable gas by the thin dielectric layer 24.

An alternating field applied across a particular segment conductor 21aand common conductor 22a will give rise to the occurrence ofillumination on the surface immediately adjacent the segment conductor21a and the common electrode 22a. This glow will be sustained on bothsurfaces for as long as the alternating potential is applied to thoseconductors. The illumination' provided by the common conductor does notcause any problems, because the illumination is masked out by the maskmember 14 and thus is not visible to an observer.

In order to aid those skilled in the art in the practice of the presentinvention, the following information for construction of one form of adisplay panel in accordance with the teachings of this invention isgiven by way of exemplification only. In the embodiment shown in FIG. 1,the mask member 14 was formed from dark-colored glass (thin plate etchedor thick film screened) having a thickness of approximately 0.002 inch.The spacing member 16 and the plate 12 were formed from plate glasshaving a thickness of one-eighth inch. The segment conductors 2la-g andthe common conductors 22a-n were formed from a material such as silkscreen silver and were deposited to a thickness of 0.0005 inch. Thesurface area of the segment conductors 21a-g is, of course, dependentupon the amount of illumination desired. A gas mixture of 99.7% neon,0.1% argon, and 0.2% nitrogen to a pressure of 35 millimeters of mercuryat room temperature was utilized in the successful operation of thedisplay panel. However, it was found that the display panel could besatisfactorily operated with pressures ranging from 16 to 70 millimetersof mercury. The alternating voltage used for exciting the gas mixturehad a magnitude of 320 volts at a frequency of kHz. with a pulse widthof 6 microseconds. However, the panel was successfully operated at 210volts. For optimum performance, the common conductor 22 is so positionedon the first side of the plate 18 that the distance from the segmentconductor 210, which is farthest away from the common conductor 22a, isnot greater than twice the distance of the nearest segment conductor 21dfrom the common conductor 22. The brightness generated by theabove-described display panel ranged from 40 to 76 foot lamberts.

A modification of the device shown in FIG. 1 and described above isshown in FIG. 2. In this embodiment, the common conductor is positionedat one side of the segmented conductor array rather than on the bottom.The mode of operation of the structure illustrated in FIG. 2 is similarto that shown in FIG. 1.

What is claimed is:

l. A plasma display device of the type wherein a plurality ofgas-containing cells are utilized for the display of intelligence,comprising:

a support member;

a plurality of segmented conductor arrays and corresponding commonconductors deposited on one surface of said support member;

a dielectric layer deposited over said segmented conductor arrays andsaid corresponding common conductors;

a cell-defining member positioned on said support member, each formedcell corresponding to the combination of one segmented conductor arrayand a common conductor;

a translucent plate positioned on said cell-defining member, therebyforming an assembly which is hermetically sealed; and

means for applying an alternating field to selected segmented conductorsof selected segmented conductor arrays and a corresponding commonconductor thereof for the ionization of a gas immediately adjacent tosaid selected segmented conductors.

2. A device according to claim 1 wherein said plasma display devicefurther includes a mask member having a plurality of openingstherethrough, said openings forming a plurality of arrays, whereby saidarrays each correspond to one segmented conductor array for furtherdefining illumination provided by the ionization of gas immediatelyadjacent selected segments of said segmented conductor arrays.

3. A plasma display device comprising:

a support member;

a plurality of segmented conductor arrays positioned on said supportmember;

a plurality of common conductors positioned on said support member, eachcommon conductor corresponding to one segmented conductor array;

a dielectric layer deposited on said support member,

- thereby coating all of said common conductors and segmented conductorarrays;

a cell-forming member positioned on said support member, saidcell-forming member forming a plurality of cells and being soconstructed that pressure-equalizing paths are formed between saidformed cells;

a mask member positioned on said cell-forming member, said mask memberhaving a plurality of openings therethrough, each opening correspondingto one segmented conductor of said segmented conductor arrays;

a transparent member positioned on said mask member,

said transparent member, said mask member, said cellforming member, andsaid support member being hermetically sealed;

means for introducing a gaseous medium into said formed cells; and

means for alternately energizing selected segmented conductors ofparticular segmented conductor arrays and a corresponding commonconductor thereof for the ionization of gas immediately adjacent saidselected segmented conductors, thus displaying intelligence in the formof illumination.

combination of a segmented conductor array and a corresponding commonconductor thereof;

means for sealing said plate, said cell-defining member, and saidadditional plate together, thereby forming a gastight structure;

means for introducing a gaseous medium into said defined cells; and

means for energizing selected segments of selected segmented conductorarrays and corresponding common conductors for presenting intelligenceinthe form of illumination conforming to a particular configuration.

1. A plasma display device of the type wherein a plurality ofgas-containing cells are utilized for the display of intelligence,comprising: a support member; a plurality of segmented conductor arraysand corresponding common conductors deposited on one surface of saidsupport member; a dielectric layer deposited over said segmentedconductor arrays and said corresponding common conductors; acell-defining member positioned on said support member, each formed cellcorresponding to the combination of one segmented conductor array and acommon conductor; a translucent plate positioned on said cell-definingmember, thereby forming an assembly which is hermetically sealed; andmeans for applying an alternating field to selected segmented conductorsof selected segmented conductor arrays and a corresponding commonconductor thereof for the ionization of a gas immediately adjacent tosaid selected segmented conductors.
 2. A device according to claim 1wherein said plasma display device further includes a mask member havinga plurality of openings therethrough, said openings forming a pluralityof arrays, whereby said arrays each correspond to one segmentedconductor array for further defining illumination provided by theionization of gas immediately adjacent selected segments of saidsegmented conductor arrays.
 3. A plasma display device comprising: asupport member; a plurality of segmented conductor arrays positioned onsaid support member; a plurality of common conductors positioned on saidsupport member, each common conductor corresponding to one segmentedconductor array; a dielectric layer deposited on said support member,thereby coating all of said common conductors and segmented conductorarrays; a cell-forming member positioned on said support member, saidcell-forming member forming a plurality of cells and being soconstructed that pressure-equalizing paths are formed between saidformed cells; a mask member positioned on said cell-forming member, saidmask member having a plurality of openings therethrough, each openingcorresponding to one segmented conductor of said segmented conductorarrays; a transparent member positioned on said mask member, saidtransparent member, said mask member, said cell-forming member, and saidsupport member being hermetically sealed; means for introducing agaseous medium into said formed cells; and means for alternatelyenergizing selected segmented conductors of particular segmentedconductor arrays and a corresponding common conductor thereof for theionization of gas immediately adjacent said selected segmentedconductors, thus displaying intelligence in the form of illumination. 4.A plasma display panel of the type wherein a plurality of gas-containingcells are utilized for the display of intelligence, comprising: a plate;an additional plate having positioned thereon a segmented conductorarray and a corresponding common conductor for each cell, said segmentedconductor arrays and said common conductors being coated by a thindielectric layer; a member for defining said cells, comprising a wallformation of glass-like material, positioned between the combination ofa segmented conductor array and a corresponding common conductor thereofand an adjacent combination of a segmented conductor array and acorresponding common conductor thereof; means for sealing said plate,said cell-defining member, and said additional plate together, therebyforming a gastight structure; means for introducing a gaseous mediuminto said defined cells; and means for energizing selected segments ofselected segmented conductor arrays and corresponding common conductorsfor presenting intelligence in the form of illumination conforming to aparticular configuration.